Typically temperature controls in countertop ovens; sample and measure the air temperature within the oven cooling chamber during cooking or defrosting a food product. Monitoring of the air temperature in the oven does not take into account that the surface temperature and the internal temperature of the food may differ greatly depending upon the consistency of the food. For example, meat may be warm to the touch and look defrosted on its external surface but in reality is still frozen at its center. Therefore the standard internal air temperature sensing devides of countertop ovens lack the ability to either defrost or cook foods accurately to a desired temperature.
Some countertop ovens, e.g. microwave ovens, have achieved greater temperature control for cooking and/or defrosting by adding a probe-like apparatus with a temperature sensitive device in the probe for use in connection with the temperature control system. While these devices may have accounted for a degree of increased reliability in sensing temperature accurately, none provide for the detection of a malfunction of the temperature sensing element. In addition, most of the probe temperature sensing circuits are used in connection with browning elements to give the food an exterior appearance similar to one achieved in a conventional gas or electric cooking oven.
Most countertop ovens defrost food by using a timing mechanism to control whatever type of heating element is used in that particular oven. This method is not particularly accurate, especially for meat products, because while certain meats may weigh the same their shape and size can vary the amount of time necessary to either defrost or cook such product. Of course, the food product does not have to be meat. The food to be cooked or defrosted may be any one of a variety of foodstuffs such as casseroles, pastries, fish, etc.